Carrousel apparatus for manufacturing, by compression molding, plastics items

ABSTRACT

An apparatus for manufacturing plastics items provided with external undercuts, comprising at least one compression molding unit (S), which is composed of an upper male mold part ( 1 ) comprising a plug ( 15 ) and of a lower female mold part ( 2 ) aligned, along a vertical axis, with the male mold part ( 1 ), means for actuating the mold parts ( 1, 2 ) between a spaced position, at which a dose of plastics sufficient to form an item is deposited in the female mold part ( 2 ), and a mating position for producing the compression molding of an item, the male mold part ( 1 ) comprising a plug ( 15 ) and an ejector ( 3, 9 ) that is associated with the plug in order to remove the molded item when the mold parts are in the spaced position, characterized in that it comprises a bushing ( 36 ) that is arranged externally and coaxially to the plug ( 15 ), a plurality of sectors ( 48 ) for forming raised portions (F) and undercuts (G) on the outer surface of the item, the sectors ( 48 ) being coupled axially to the bushing ( 36 ) and being able to expand with respect to the plug ( 15 ), means for actuating the sectors ( 48 ) between a position that produces mating with the plug ( 15 ) in order to allow the compression molding of the item and the molding of the raised portions and undercuts, and a spaced position in order to allow to remove the molded item from the plug ( 15 ).

BACKGROUND OF THE INVENTION

[0001] The present invention relates to a carrousel apparatus formanufacturing, by compression molding, plastics items.

[0002] Compression molding apparatuses generally comprise a carrousel,which can rotate about a vertical axis and on which a plurality ofangularly spaced molding units are installed. Each unit comprises anupper male element (plug) aligned with a lower female mold part(cavity).

[0003] In order to obtain the item, a dose of semifluid plastics isintroduced in the female mold part and is pressed by means of a relativemovement of the two mold parts in order to obtain the item.

[0004] In the manufacture of caps for closing containers provided withinternal undercuts (for example screw caps), the molded cap, after themold parts have been opened, remains attached to the plug and is removedby means of an ejector, utilizing the elasticity of the plastics thathas not yet hardened.

[0005] In the case of caps having external undercuts, it is not possibleto perform removal by simply pushing downward the ejector, since the capcannot retract inward.

SUMMARY OF THE INVENTION

[0006] The aim of the present invention is to obviate the above citeddrawbacks of known devices, i.e., to provide a carrousel apparatusprovided with means that allow to form items, particularly hollow items,such as caps provided with raised portions and undercuts on their outersurface.

[0007] Within this aim, an object of the present invention is to providean apparatus in which the cap forming means assist the extraction of themolded caps from the mold.

[0008] This aim and this object are achieved by the present apparatus,whose characteristics are defined in the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Further characteristics and advantages will become betterapparent from the detailed description of a preferred but not exclusiveembodiment of a carrousel apparatus for manufacturing screw caps bycompression molding of plastics, illustrated only by way ofnon-limitative example in the accompanying drawings, wherein:

[0010]FIG. 1 is a sectional view, taken along a vertical plane, of amolding unit of the apparatus;

[0011]FIG. 2 is an enlarged-scale view of the upper part of the unit ofFIG. 1;

[0012]FIG. 3 is an enlarged-scale view of the lower part of the unit ofFIG. 1;

[0013]FIG. 4 is a sectional view of a detail of the unit of FIG. 1;

[0014]FIG. 5 is a sectional view, taken along the line V-V of FIG. 4;

[0015]FIGS. 6, 7 and 8 are views of the lower part of the unit in threesuccessive operating conditions;

[0016]FIGS. 9 and 10 are two sectional views, taken along a verticalplane, of the lower part of a second embodiment.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] With reference to FIGS. 1 to 5, the apparatus is constituted by acarrousel, which rotates about a vertical axis Z and supportsperipherally a plurality of units S for the molding of caps that consistof screw caps A made of plastics. One of said caps is illustrated moreclearly in FIG. 8.

[0018] Hereinafter, it is assumed that said caps A are composed of a cupB provided with an internal thread C and of a tamper-evident band Dprovided with inner teeth E and with an outer annular ridge F. The bandD forms, together with the rim of the cup, an outer step G.

[0019] Each unit S is composed of an upper male mold part, generallydesignated by the reference numeral 1, and of a lower female mold part,generally designated by the reference numeral 2, which are mutuallycoaxial along an axis X that is parallel to the axis Z. The female moldpart 2 can be actuated against the male mold part 1 by means of ahydraulic jack, which is not shown.

[0020] The male mold part 1 comprises a plate 3 (see FIG. 3), which isscrewed, by means of a tubular tang 4, into a sleeve 5 b, which is inturn screwed to the lower end of a sleeve 5 a so as to form a singlehollow stem 6 (FIG. 1).

[0021] A hollow tube 7 is inserted hermetically in the tubular tang 4and is composed of two portions 7 a and 7 b which are screwed together;said hollow tube forms, together with the hollow stem 6 (i.e., with thesleeves 5 and 5 a), a tubular interspace 8. The sleeve 5 b has, at itslower end, a wider portion 9 in which the plate 3 is centeredhermetically. The wider portion 9 with the tubular tang 4 forms achamber 10 that is connected to the interspace 8 through openings 11 ofthe tang 4. Furthermore, the chamber 10 is connected to the inside ofthe hollow tube 7 through openings 12 formed in the region of the tang 4directly above the plate 3.

[0022] The wider portion 9 forms, together with the sleeve 5 b of thehollow stem 6, a step 9 a for resting thereon the shoulder 13 b of atubular element 13 provided with a lower portion 13 a that is shaped soas to have a helical outer slot 14 and recesses 13 c which aredistributed peripherally (see FIG. 8). As shown more clearlyhereinafter, the hollow stem 6 is controlled by actuation elementswhich, starting from a position in which the step 9 a abuts against theshoulder 13 b, impart thereto a downward stroke, which allows the plate3 and the wider portion 9 to descend below the portion 13 a. In thismanner, the step 9 a abuts against the shoulder 13 b. The portion 13 aand the plate 3, together with the edge of the cylindrical wider portion9 in which it is centered, form the forming plug 15 (see FIG. 6) thatdetermines the internal profile of the cap A, i.e., the thread C, thebottom H of the cup B, and the internal protrusions of thetamper-evident band D for retaining the cap on the container to which itis applied. In the illustrated example, said protrusions, in order tomatch the recesses 13 c, consist of teeth E (see FIG. 8), but they canhave any shape and in particular they can be constituted by an annularlip.

[0023] When the hollow stem 6 is actuated so as to descend, the plate 3and the cylindrical wider portion 9 protrude from the tubular portion 13a and, by acting on the bottom H of the cap A, act as an ejector forsaid cap, hereinafter designated by the reference numerals 3 and 9.

[0024] The upper end of the portion 7 a of the hollow tube 7 isconnected hermetically in a seat 16 (see FIG. 2) of the top of the stem6, which is in turn inserted hermetically in a seat 17 of a body 18 andis retained by a screw 19. A connector 20 is arranged on the body 18,and two holes 21, 22 are formed therein; said holes are connected to thedelivery and to the return of a cooling liquid. The holes 21, 22 areconnected to the hollow tube 7 and the tubular interspace 8 by means ofpassages 23, 24 of the body 18 and of the stem 6, so as to convey thecooling liquid into the chamber 10 and ensure the cooling of the plug 15and the setting of the plastics of which the cap A is made.

[0025] The hollow stem 6, with its portion 5 a, is guided slidingly in atubular element or sleeve 25, which is accommodated coaxially in acylindrical seat 26 of a supporting body that is part of the structureof the carrousel. In practice, said body is constituted by a sort ofrotary drum 27, which is mounted on a vertical shaft whose axis Z is therotation axis of the carrousel. The sleeve 25 is suitable, with itslower end, to act as an abutment for the tubular element 13 during themolding of the cap A.

[0026] A bush 28 is inserted in the seat 26 and abuts, with an upperannular lip 29, on the edge of the seat 26. An external flange 32 of thesleeve 25 rests on the annular lip 29, with the interposition of a ringof elastic material 30 and of a spacer ring 31. Retention elements 33engage on the flange 32 and, by means of screws (not shown in thedrawing), lock on the upper face of the drum 27 the sleeve 25 and thebush 28 coaxially to each other and to the seat 26.

[0027] The bush 28 forms, together with the tubular element 23 and thesleeve 25, a compartment 34 in which there is a tube 35, which can slideon the tubular element 13, and there is a bushing 36, which can slide onthe tube 35. The lower end 35 a of the tube 35 is chamfered externallyin a conical fashion.

[0028] Axial sliding bearings 37, 38 are interposed between the tube 35and the bushing 36 and between said bushing and the bush 28.

[0029] In the compartment 34, above the bushing 36, there is acylindrical case 39, which rests, with a lower inner lip 40, on the topof the bushing 36. A center bearing 41 is centered on the case 39, and aring 42 of elastic rubber-like material is interposed between saidcenter bearing and the flange 32 of the sleeve 25.

[0030] The tube 35 has, at the top, an outer lip 43 for abutment on theinner lip 40 of the case 39, which supports a center bearing 44 for theresting of a cylindrical spring 45. The spring 45 is accommodated in anannular chamber 45 a comprised between the sleeve 25 and the case 39 andabuts against the center bearing 41. The compression strokes of thespring 45, i.e., the upward strokes of the tube 35, are limited by theabutment of the center bearing 44 against a shoulder 46 of the sleeve25.

[0031] The tube 35 has, at its lower end, a circular hollow 47 (see FIG.3) for the vertical retention of four sectors 48, which are arranged soas to constitute a forming ring for a region of the tamper-evident bandD of the plug A and at the same time act as an aid for the ejection ofthe cap A performed by the plug 15 after molding the plastics andopening the mold.

[0032] The sectors 48 cover a 90° angle about the axis X and areprovided with collars 49, which engage in the hollow 47.

[0033] Furthermore, the sectors 48 protrude downward, beyond the lowerend of the sleeve 35, with a conical segment 50, which ends with an edge51 that is concentric to the axis B and is provided with a slot 51 a,which faces the portion 13 a of the tubular element 13. The edge 51therefore allows to form, on the outside of the cap A, the step G andthe collar F, i.e., undercuts which, in conventional molds, contrast theextraction of the molded item.

[0034] The ring constituted by the sectors 48 is substantiallyfrustum-shaped, and on the outer surface of each sector there is adovetail slot 52, which lies on a radial plane that passes through theaxis X. The slots 52 constitute sliding guides for keys 53, which arefixed in seats 54 of a conical ring 55 that is centered and fixed bymeans of screws 56 coaxially to the axis X under a plate 57, which isslidingly guided on the bushing 36.

[0035] The keys 53 diverge downward with the same angle as the slots 52,so that when the bushing 36 is actuated so as to descend, the sectors 48move mutually apart in a radial and circumferential direction and remainengaged axially with the hollows 47 by means of the collars 49.

[0036] The plate 57 is rigidly coupled to the rotary drum 27 by means ofa pin 58 (see FIGS. 1 and 4), which is fixed with one end under saiddrum and is provided, at its opposite end, with a mushroom-like part 59.The pin 58 can slide in a hole 60 formed in a wing 61 of the plate 57,and on the portion of the pin 58 that lies between the wing 60 and thedrum 27 there is a spring 62 which, by means of its opposite ends, restson the wing 61 and on the drum 27, with bushings 63 and 64 interposed.

[0037] The spring 62 keeps the plate 57 rested on the sectors 48, whichaccordingly, during the descent of the bushing 36, remain closed in aring-like arrangement until the wing 61 abuts against the mushroom-likepart 59 of the pin 58.

[0038] When the wing 61, after performing a stroke “h” from a presetraised position, abuts against the mushroom-like part 59, by means ofthe additional stroke of the bushing 36 the sectors 48 are forced, bythe engagement of the keys 53 in the slots 52, to follow a path thatdiverges downward and causes the edges 51 to be spaced from the lowerthreaded portion 13 a of the tubular element 13. In order to actuate thebushing 36 there is a column 65 (see FIG. 2), which can slide, by meansof bearings 66 and 67, in a seat 68 of the drum 27 that is parallel tothe seat 26 and whose axis is radially internal with respect to the axisX of the unit S.

[0039] An arm 69 (see FIGS. 1 and 3) is fixed to the lower end of thecolumn 65 by means of a screw 68 and is provided with an opening 70,through which the bushing 36 is guided. The opening 70 is shaped so thatits edge remains gripped between two collars 71, 72 of the bushing 36,so as to provide an axial connection thereof with the column 65. Thesleeve 36 can be positioned at an angle to the arm 69 by means of a pin73, which is guided in a radial hole 73 a of the arm 69 and is providedwith a knob 74; by acting on said knob in contrast with a return spring75, it is possible to cause the engagement of the pin 73 in any one of aplurality of holes formed in the sleeve 36 between the collars 71 and72.

[0040] The column 65 protrudes above the drum 27 with a tang 76 (seeFIG. 2), which slidingly supports, with the aid of bearings 77 and 78, asleeve 79. The sleeve 79 has a collar, which acts as a shoulder 80, andis surmounted by a washer 81 that rests on the upper edge of the sleeve79. A precompressed spring 82 rests on the washer, and its top end restsagainst a bushing 83, which is fixed to the upper end of the tang 76 inan adjustable manner in order to be able to adjust the precompression ofsaid spring 82.

[0041] A ring 84 is screwed onto the sleeve 79 until it abuts againstthe shoulder 80, and a stem 85 protrudes from said ring 84 and supportstwo rollers 86, 87. The roller 87 is engaged in a cam 88, which isrigidly coupled to the fixed structure of the apparatus and is thereforestationary with respect to the drum 27. The roller 86 is guided in avertical slot of a bracket (not shown in the drawing), which is fixed onthe drum 27 and is meant to prevent the rotation of the sleeve 79 withrespect to the tang 76.

[0042] The cam 88 has a circular extension that is concentric withrespect to the axis Z of the carrousel, so as to produce axial movementsof the column 65, and, by way of the connection provided by the arm 69,of the bushing 36.

[0043] The axial movement of the bushing 36 is combined with themovement of the ejector 3, 9. For this last movement, there is a roller89, which is mounted on the cylindrical body 18 at the top end of thestem 6 and is capable of following an axial cam 90, which is alsostationary and concentric with respect to the cam 88.

[0044] The roller 89 is retained on the profile of the cam 90 by aspring 91, which rests on the flange 32 in a downward region and on ashoulder 92 of the body 18, with a cup-shaped washer 93 interposed, inan upper region.

[0045] In order to prevent the rotation of the stem 6 and of the body 18about their own axis, there is a bridge 94, which is fixed to the top oftwo columns 95, 96 and has an opening 97 through which the cylindricalbody 18 is slidingly guided.

[0046] An axial slot 98 is formed in the outer surface of thecylindrical body 18, and a key 99 slidingly engages therein; said key isfixed to the bridge 94 and protrudes into the opening 97, allowing thebody 18 to slide, but not rotate, in the opening 97.

[0047] The operation of the described apparatus is as follows. Duringthe rotation of the carrousel, a dose of plastics having a pastyconsistency is deposited in the cavity of the female mold part 2. Inthis step, the female mold part 2 is lowered with respect to the malemold part 1, while the plug 15, by means of the spring 91, is actuatedinto the upward stop position determined by the abutment of the step 9 aof the portion 9 against the shoulder 13 b of the tubular element 13 andof the top end thereof against the lower end of the sleeve 25.

[0048] In this stop position, the lower end 35 a of the tube 35 liesabove the edges 51 of the sectors 48, in front of the recesses 13 c ofthe portion 13 a.

[0049] When the female mold part 2 is lifted hydraulically, the edges 51of the sectors 48 initially abut against the shoulder 100 of the moldpart 2 (see FIG. 1) and then against the lower end 35 a of the tube 35,thus delimiting the cap forming chamber. As the upward motion of thefemale mold part 2 continues, the plastics is distributed into theforming chamber, filling it and causing, owing to its ownincompressibility, the female mold part to stop in the final position,in which the cap A has assumed its final shape.

[0050] It should be noted that the spring 45, by acting on the tube 35and, by means of the lip 44 of the case 39, on the bushing 36, keeps theedges 51 rested on the shoulder 100 and allows to vary the volume of theforming chamber according to the quantitative variations of the dose ofplastics that is deposited in the cavity of the female mold part.

[0051] When the plastics has reached a suitable setting point,determined by feeding cooling liquid into the chamber 10 and into thesimilar chamber of the female mold part, so that plastic deformations ofthe cap are no longer a concern, the descent of the female mold part 2is actuated. However, the cap A is retained on the plug 15 by theengagement of the thread C in the slot 14 of the portion 13 a and by theretention of the tamper-evident band D between the outer surfacecomposed of the edges 51 of the sectors 48 and the conical end 35 a ofthe tube 35 and the inner surface, composed of the region of the portion13 a that is provided with the recesses 13 c.

[0052] When the female mold part 2 is spaced sufficiently from the plug15, the downward movement of the column 65 and of the hollow stem 6 isactuated by means of the cams 88 and 90.

[0053] The descent of the hollow stem 6 causes (see FIG. 6) the loweringof the plug 15 to the stroke limit level, at which the tamper-evidentband D lies below the conical end 35 a of the tube 35. At the same time,the descent of the column 65, by means of the arm 69, determines thedescent of the bushing 36 and the downward actuation of the sectors 48.

[0054] The descent stroke of the column 65 comprises a first portion,which is equal to the stroke of the plug 15, during which the conicalring 55, by way of the spring 62 that acts on the wing 61 of the plate57, remains engaged on the sectors 48 and prevents their opening. Duringsaid first portion, the descent of the sectors 48 is accompanied by thedescent of the plug 15 and the edges 51 therefore remain in restingcontact on the step G of the molded cap A.

[0055] At the end of the first portion of the stroke, the wing 61 abutsagainst the mushroom-like part 59 of the pin 58, which stops the descentof the plate 57 and of the ring 55, while the tubular element 13, by wayof the presence of a top collar 13 d (see FIG. 2) that abuts on ashoulder 35 b of the tube 35, stops with respect to the stem 6.

[0056] In particular, it should be noted that the descent of the tube 35is prevented by the abutment of the outer lip 43 against the inner lip40 of the case 39, which in the meantime, by means of the spring 45, hasmoved so as to rest against the internal shoulder 28 a of the bush 28.

[0057] The halting of the tube 35 allows the formation, above the edges51, of an annular opening 101 (see FIG. 6), into which thetamper-evident band D can expand in order to allow the teeth E toprotrude from the respective recesses 13 c of the portion 13 a.

[0058] With the second portion of the descent stroke of the column 65and of the hollow stem 6 (see FIG. 7), the thrust applied to the sleeve36 and to the stem 6 actuates downward the sectors 48 and the ejector 3,9, which by acting respectively on the step G and on the bottom H of thecap A cause the disengagement of the thread C from the slot 14 and ofthe teeth E from the respective recesses 13 c of the portion 13 a,allowed by the elasticity of the plastics, which allows the cup B toexpand radially and allows the tamper-evident band D to open out intothe opening 101.

[0059] As they continue their descent, the sectors 48 are forced, by theoblique orientation of the guides 52 and 53, to move further away fromthe peripheral region of the cap until they leave the step G. At thispoint, the complete extraction of the cap A is entrusted solely to theejector 3, 9, whose thrust continues until the teeth E have descendedbelow the lower edge of the portion 13 a, beyond which the cap A canfall freely into a collection area.

[0060] It is evident that the fundamental prerogative of the presentinvention is that the sectors 48 allow to act both as elements forforming undercuts that lie externally with respect to the cap and aselements that assist cap extraction. The thrust applied axially to thecylindrical wall of the cap by the sectors 48 in fact facilitates thewidening of the cap that is required in order to allow the ejector 3, 9to force the exit of the thread C from the helical slot 14 withoutcausing the material of the cap to yield.

[0061] By contrast, it should be noted that in conventional moldingunits, in which cap extraction is entrusted solely to the ejector, thethrust applied by said ejector to the bottom of the cap causes thecylindrical wall of the cup B to clamp more tightly onto the tubularportion 13 a. This fact obviously requires more force to remove thethread C from the slot, with severe consequences for the integrity ofthe cap.

[0062] The described apparatus is susceptible of numerous variations inorder to deal with the different types of product.

[0063]FIGS. 9 and 10 are sectional views of the lower part of a unit forthe compression molding of the lower part L of a container made ofplastics, which is composed of a frustum-shaped plate M and anexternally threaded neck N.

[0064] In FIGS. 9 and 10, the elements constituting the unit that areidentical or equivalent to those of the unit shown in FIGS. 1 to 8 aredesignated by the same reference numerals.

[0065] As clearly shown, the unit of FIGS. 9 and 10 is constructivelysimpler, owing to the fact that the part L to be molded is not providedwith inner undercuts which, in order to be able to disengage from therespective molding recesses of the plug 15 during part extraction, wouldhave to be able to expand outward, as allowed for example by the end 35a of the tube 35 of the molding unit described earlier. The absence ofthe inner undercuts therefore allows to remove the part simply byopening the conical segments 51.

[0066] The disclosures in Italian Patent Application No. B02000A000704from which this application claims priority are incorporated herein byreference.

1. An apparatus for manufacturing plastics items provided with externalundercuts, comprising at least one compression molding unit (S), whichis composed of an upper male mold part (1) comprising a plug (15) and ofa lower female mold part (2) aligned, along a vertical axis, with saidmale mold part (1), means for actuating said mold parts (1, 2) between aspaced position, at which a dose of plastics sufficient to form an itemis deposited in the female mold part (2), and a mating position forproducing the compression molding of an item, said male mold part (1)comprising a plug (15) and an ejector (3, 9) that is associated withsaid plug in order to remove said molded item when said mold parts arein said spaced position, characterized in that it comprises a bushing(36) that is arranged externally and coaxially to said plug (15), aplurality of sectors (48) for forming raised portions (F) and undercuts(G) on the outer surface of said item, said sectors (48) being coupledaxially to said bushing (36) and being able to expand with respect tothe plug (15), means for actuating said sectors (48) between a positionthat produces mating with said plug (15) in order to allow thecompression molding of said item and the molding of said raised portionsand undercuts, and a spaced position in order to allow to remove saidmolded item from said plug (15).
 2. The apparatus according to claim 1for manufacturing hollow items, such as caps (A) for closing containers,comprising a plurality of compression molding units (S) arranged on acarrousel (27) that rotates about a vertical axis (Z), each unitcomprising an upper male mold part (1) and a lower male mold part (2),which are aligned along an axis (X) that is parallel to said rotationaxis (Z) of the carrousel, means for actuating said molds (1, 2) betweena spaced position, at which a dose of plastics sufficient to form anitem is deposited in the female mold part (2), and a mating position inorder to determine the compression molding of said caps, said male moldpart (1) comprising a tubular element (13) that ends with a tubularportion (13 a) that is contoured for the internal profile of said itemsand forms a plug (15) with an ejector (3, 9) associated with a tubularstem (6) which is guided in said tubular portion (13 a) and is actuatedby cam means (90) between a position for completing the inner profile ofsaid items and a position for removing said items from said tubularportion (13 a), characterized in that it comprises: a bushing (36),which is arranged externally and coaxially to said tubular element (13);a plurality of sectors (48) for forming raised portions (F) andundercuts (G) on the outer surface of said items, said sectors (48)being retained axially to said bush (36) and being able to expand withrespect to said tubular portion (13 a); means for actuating said sectorsbetween a position for mating with said tubular portion (13 a) in orderto allow the compression molding of said items and the formation of saidraised portions and undercuts on the outer surface of said items, and aspaced position in order to allow the removal of said molded items fromsaid plug (15).
 3. The apparatus according to claim 2, characterized inthat said actuation means of said sectors (48), for each molding unit(S), comprise an element (57) which is guided on said bushing (36) andis rigidly coupled to said sectors (48) by inclined guides (52, 53)which lie on planes that are radial to the axis of said plug (15) andconverge on it, said bushing (36) being axially rigidly coupled to acolumn (65), which is guided in said carrousel (27) and is controlled bycam means (88) suitable to actuate said element (57) in order to movesaid sectors (48) along said guides (52, 53) between said matingposition and said spaced position with respect to said tubular portion(13 a).
 4. The apparatus according to claim 3, characterized in thatelastic means (62) are arranged between said element (57) and saidcarrousel (27) and act on said element (57) so as to keep said sectors(48) mated with said tubular portion (13 a) during the molding of theitems (A) and along a first portion of the ejection stroke of saidejector (3, 9), a stroke limiter (59) being provided for said element(57) and being arranged so as to determine, along a second portion ofthe ejection stroke of said ejector (3, 9), the sliding of said sectors(48) along said inclined guides (52, 53) and the expansion of saidsectors (48) in said spaced position in order to allow to remove theformed items by means of said ejector (3, 9).
 5. The apparatus accordingto claim 4, characterized in that said elastic means are constituted bya spring (62), which is mounted on a pin (58) fixed to said carrouseland is interposed between said carrousel and said element (57), said pin(58) being provided with said stroke limiter (59) for said element (57).6. The apparatus according to one of claims 2 to 5 for manufacturingscrew caps (A) for closing containers, said caps comprising acylindrical cup (B) provided with an internal thread (C) and with atamper-evident band (D) with internal protrusions (E) and externalraised portions (F) and undercuts (G), comprising a plurality ofcompression molding units (S) arranged on a carrousel (27) that rotatesabout a vertical axis (Z), each unit comprising an upper male mold part(1) and a lower female mold part (2), which are aligned along an axis(X) that is parallel to said rotation axis (Z) of the carrousel, meansfor the hydraulic lifting of said female mold part (2) between a loweredposition, at which a dose of plastics sufficient to form a cap isdeposited in the female mold part (2), and a mating position, forproducing the compression molding of said caps, said male mold part (1)being constituted by a plug (15) that is composed of: a tubular element(13), which ends with a contoured tubular portion (13 a) provided with ahelical slot (14) and with recesses (13 c) for forming the thread (C)and, respectively, internal protrusions (E) of said caps; a hollow stem(6), which is guided in said tubular element (13) and has an end (84)controlled by an actuation cam (90) and an opposite end provided with anejector (3, 9) accommodated slidingly in said tubular portion (13 a); atube (35), which can slide on said tubular element (13) and has an end(13 a) that can be superimposed on said recesses (13 c); a bushing (36),which can slide on said tube (35); a plurality of sectors (48), whichare axially retained on said bushing (36) and can expand radially withrespect to said tubular portion (13 a), said sectors (48) being providedwith segments (50) that form edges (51) that protrude toward saidtubular portion (13 a) at a level below said end (35 a) of said tube(35); and an element (55, 57) for actuating the sectors (48) of eachmolding unit (S), which is guided on said bush (36) and rigidly coupledto said sectors (48) by inclined guides (52, 53), which lie on planesthat are radial to the axis (X) of said plug (15) and converge toward apoint of said axis, said bushing (36) being axially rigidly coupled to acolumn (65), which is guided in said carrousel (27) and is controlled bycam means (88) for controlling said element (57), said cam means (88,90) for controlling said element (57) and said ejector (3, 9) beingmutually coordinated so that when the female mold part (2) rises in theposition for closing the mold, said edges (51) and said ends (35 a) ofthe tube (35) are arranged opposite said recesses (13 c) in order toallow the formation of the tamper-evident band (D), while when thefemale mold part (2) descends into the mold opening position, saidtubular portion (13 a) and said sectors (48) descend with respect tosaid tube (35) so as to form an opening (101) between said edges (51)and said end (35 a) and the positioning of said tamper-evident band (D)at said opening (101), then the disengagement of said edges (51) of thesectors (48) from the formed cap (A), and finally the removal of the capfrom said tubular portion (13 a).